Zero Tolerance and the Principles of Infection Management

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Chapter: Pharmaceutical Microbiology : Public Health Microbiology: Infection Prevention And Control

As a result of the implementation of the measures outlined above, the rates of particular HCAIs have fallen significantly in several countries. The application of the central venous catheter care bundle by intensive care units in the USA has resulted in a steep reduction in cases of catheter-related bacteraemia and, in some cases, long periods with no such infections.



As a result of the implementation of the measures outlined above, the rates of particular HCAIs have fallen significantly in several countries. The application of the central venous catheter care bundle by intensive care units in the USA has resulted in a steep reduction in cases of catheter-related bacteraemia and, in some cases, long periods with no such infections. In England, the package of measures aimed at MRSA bacteraemias resulted in a 65% decrease in cases reported from the 2004 target base-line to 2009. These improvements have enabled the promotion of a zero tolerance approach to HCAI. This does not mean that there will be no infections (this is microbiologically and clinically implausible) but does mean that we can apply a zero tolerance approach to avoidable infections and to poor clinical practice such as inadequate compliance with hand hygiene requirements and imprudent antibiotic prescribing. The aim is to do everything right every time.


The general principles of infection management apply to HCAIs as they do to all types of infection, but it is particularly important to have reliable application of the principles where there is the risk of spread amongst vulnerable patients. Clinical staff need to have a high index of suspicion that a patient may be developing an infection and initiative appropriate confirmative diagnostic tests quickly. There should be prompt isolation of a patient suspected of being infected and specific treatment instituted along with infection prevention and control measures to prevent further spread. As well as these universal principals, there are some specific prevention and control measures aimed at particular infections.




The reductions in MRSA bacteraemia achieved in UK hospitals and elsewhere as part of the targeted approach has been mostly the result of emphasis on hand hygiene,improved aseptic practices and the care bundles/HII approach for invasive procedures, particularly intravenous central catheter and peripheral cannula insertion and care. Implementation of these measures has been backed by the commitment of managers to reduce infection rates. These general improvements in infection prevention and control procedures would also be expected to help prevent other courses of bacteraemias linked to intravenous catheters and cannulae.


The further measure that is specific to the prevention of MRSA infections overall (wound and soft tissues infections, VAP, etc., as well as bacteraemias) is screening of patients before admission to hospital (when admission is planned or ‘elective’) or on admission in respect of emergency admissions. The principles behind such screening are that colonization of the nose and/or skin sites generally precedes clinical infection and that a colonized patient (otherwise referred to as a ‘carrier’) is at risk of developing an MRSA infection themselves and also a potential source of transmission to others. For such screening a swab is taken from the anterior nares, and also from the other skin carriage sites of perineum and axilla if considered appropriate, as well as from any surface lesions such as a chronic ulcer. Laboratory examination of the swab can be based upon convention selective culture for MRSA (which has a minimum turnaround time of 24–48 hours) or more expensive molecular methods based on PCR (polymerase chain reaction) methodology when a rapid result is considered to give significant benefit. Patients found to be colonized with MRSA are generally then given a ‘decolonization’ or ‘suppressive’ treatment regimen of nasal mupirocin cream and an antiseptic skin wash and shampoo for 5 days. This is very effective in reducing the bioburden in MRSA colonization in the short term, thus reducing the risk of infection for the individual patient and the risk of transmission to other. However, colonization may recur over a period of several months in 40% or more individuals. Nevertheless, the suppression of colonization will have covered the period of particular vulnerability and the time when they would be more likely to be a source of transmission. Screening and decolonization were part of the ‘search and destroy’ approach to MRSA infection developed in the UK in the1980s. It was also adopted elsewhere and has continued to be very effective in helping maintain low levels of MRSA infection and low levels of colonization in countries such as the Netherlands, parts of Scandinavia, and Western Australia. This approach was not maintained in most parts of the UK during the1990s but has been reintroduced as part of the MRSA control measures in various ways in the UK countries in more recent years. Screening of all patients admitted to NHS hospitals has been introduced in England, whereas other countries have adopted wide-spread but more restricted, risk-based approaches to selecting patients for screening. The risk factors are generally age (>65 or 70 years), previous MRSA carriage, previous hospital admission, residence in a nursing home or residential care home, and the presence of a chronic disease. The most appropriate approach will become evident as these different regimens are applied in different healthcare settings.


Screening for Staph. aureus more generally, not specifically MRSA, has been used as part of outbreak control measures over many years but has not been adopted on a routine basis. However, modern approaches to MRSA screen could also enable screening for any Staph. aureus strain in particular vulnerable groups.


Clostridium difficile Infection


The emergence of CDI has been a complication of modern medical care compounded by inadequate attention to antibiotic stewardship and infection prevention and control measures. Elderly patients are the most vulnerable to this infection (75% of cases are in people >65 years old) but severe disease can occur in younger patients also. The major precipitating factor is the use of broad-spectrum antibiotics. In the UK, guidance produced in 1994 was reviewed and an updated document was published in 2009. This recommended the application of a mnemonic protocol (SIGHT) for managing suspected and then proven cases:


• Suspect that a case of diarrhoea maybe infective when there is not a clear alternative cause for the diarrhoea

• Isolate the patient and contact the infection control team

• Gloves and aprons must be worn for all contact with the patient and their environment

• Hand washing with soap and water before and after each contact with the patient and their environment

• Test the stool for Cl. difficile toxins by sending a specimen immediately.


CDI itself then needs to be treated as a major diagnosis in its own right (not just a minor complication of the underlying disease). Sufficient isolation capacity is required for single room accommodation of cases, but in outbreak situations it may be necessary to cohort patients in designated CDI isolation wards. Cleanliness and use of sporicidal disinfectants (currently only chlorine-releasing agents are recommended) are important in CDI control.


There should also be a major focus on antibiotic stewardship. The guidance recommends that hospitals should establish antimicrobial management teams comprising antimicrobial pharmacists, consultant microbiologist, or infectious diseases specialist, and other clinicians as appropriate. The team should develop restricted guide-lines to promote the use of narrow-spectrum agents and avoid, where reasonably possible, clindamycin and the second-and third-generation cephalosporins (especially in elderly patients), while minimizing the use of fluoroquinolones, carbapenems and prolonged courses of aninopenicillins.




It is difficult to prevent norovirus introduction because of the rapid onset of illness, but it should be stressed to all staff, patients and visitors that people should stay away from health and social care settings if they or their families are suffering from this type of vomiting and diarrhoea. When cases occur in health or residential care settings, prompt action is essential. Patients should be isolated at the first signs of the infection (which is often dramatic onset of the vomiting and diarrhoea). Patients or residents and staff who were in the same area should be quarantined to reduce the risk of wider spread as more cases occur in those exposed. Individual cases often trigger outbreaks and as soon as this is recognized to be happening, the ward or residential unit should be closed to further admissions until the outbreak has ended amongst those (patients/residents and staff) already exposed. Because of the extensive environmental contamination, cleaning and disinfection of the affected areas is an important part of control. Areas contaminated with vomitus and faeces, which is common in these infections, should be promptly cleaned and disinfected with chlorine-based disinfectant. When the outbreak is over, patients or residents need to be moved elsewhere and a thorough deep clean of the affected area (ward, unit, etc.) including disinfection with a chlorine-releasing disinfectant should be done before any patients or residents are readmitted.


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